/*

         Copyright 2007 Alexey Akhunov

    Licensed under the Apache License, Version 2.0 (the "License");

    you may not use this file except in compliance with the License.

    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software

    distributed under the License is distributed on an "AS IS" BASIS,

    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    See the License for the specific language governing permissions and

    limitations under the License.

 */

 package diy.middleware;

 import java.io.File;

 import java.io.FileOutputStream;

 import java.io.IOException;

 import java.lang.ref.PhantomReference;

 import java.lang.ref.Reference;

 import java.lang.ref.ReferenceQueue;

 import java.nio.ByteBuffer;

 import java.nio.CharBuffer;

 import java.nio.channels.FileChannel;

 import java.nio.charset.Charset;

 import java.nio.charset.CharsetEncoder;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.Timer;

 import java.util.TimerTask;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 import java.util.concurrent.atomic.AtomicLong;

 public class QueueSizeMonitor extends TimerTask implements Monitor {

         private ReferenceQueue<Object> refQueue = new ReferenceQueue<Object>();

         private ThreadLocal<Object> threadKey = new ThreadLocal<Object>() {

                 @Override

                 protected Object initialValue() {

                         return new Object();

                 }

         };

         private ThreadLocal<ConcurrentMap<String,AtomicLong>> tCounters = new ThreadLocal<ConcurrentMap<String,AtomicLong>>();

         private Map<Reference<Object>,Map<String,AtomicLong>> refs = new HashMap<Reference<Object>,Map<String,AtomicLong>>();

         private FileChannel fileChannel;

         private CharBuffer charBuffer = CharBuffer.allocate(65536);

         private ByteBuffer byteBuffer = ByteBuffer.allocate(131072);

         private CharsetEncoder encoder = Charset.forName("UTF-8").newEncoder();

         private final static String CLOSING_TAG = "</series>\n";

         private String filename;

         private long interval;

         public void init() throws Exception {

                 fileChannel = new FileOutputStream(new File(filename)).getChannel();

                 charBuffer.clear();

                 charBuffer.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");

                 charBuffer.append("<series>\n");

                 charBuffer.append("</series>\n");

                 charBuffer.flip();

                 byteBuffer.clear();

                 encoder.encode(charBuffer, byteBuffer, true);

                 byteBuffer.flip();

                 while (byteBuffer.hasRemaining()) {

                         fileChannel.write(byteBuffer);

                 }

                 Timer timer = new Timer();

                 timer.scheduleAtFixedRate(this, 0, interval);

         }

         /**

          * Increments counter for a key.

          * @param delta

          * @param key

          */

         public void count(long delta, String key) {

                 ConcurrentMap<String,AtomicLong> counterMap = tCounters.get();

                 if (counterMap == null) {

                         counterMap = new ConcurrentHashMap<String, AtomicLong>(10,0.75f,1);

                         synchronized (refs) {

                                 refs.put(new PhantomReference<Object>(threadKey.get(),refQueue), counterMap);

                         }

                         tCounters.set(counterMap);

                 }

                 AtomicLong counter = counterMap.get(key);

                 if (counter == null) {

                         counterMap.put(key, new AtomicLong(delta));

                 } else {

                         counter.addAndGet(delta);

                 }

         }

         private Map<String,AtomicLong> aggregated = new HashMap<String,AtomicLong>();

         private Map<String,AtomicLong> deads = new HashMap<String,AtomicLong>();

         @Override

         public void run() {

                 Reference ref;

                 while ((ref = refQueue.poll()) != null) {

                         Map<String,AtomicLong> dead;

                         synchronized (refs) {

                                 dead = refs.remove(ref);

                         }

                         for (Map.Entry<String, AtomicLong> entry: dead.entrySet()) {

                                 long value = entry.getValue().get();

                                 if (value == 0) {

                                         continue;

                                 }

                                 AtomicLong aCounter = deads.get(entry.getKey());

                                 if (aCounter == null) {

                                         deads.put(entry.getKey(), new AtomicLong(value));

                                 } else {

                                         aCounter.addAndGet(value);

                                 }

                         }

                 }

                 for (Map.Entry<String, AtomicLong> entry: deads.entrySet()) {

                         long value = entry.getValue().get();

                         if (value == 0) {

                                 continue;

                         }

                         AtomicLong aCounter = aggregated.get(entry.getKey());

                         if (aCounter == null) {

                                 aggregated.put(entry.getKey(), new AtomicLong(value));

                         } else {

                                 aCounter.addAndGet(value);

                         }

                 }

                 synchronized (refs) {

                         for (Map<String,AtomicLong> counterMap: refs.values()) {

                                 for (Map.Entry<String, AtomicLong> entry: counterMap.entrySet()) {

                                         long value = entry.getValue().get();

                                         if (value == 0) {

                                                 continue;

                                         }

                                         AtomicLong aCounter = aggregated.get(entry.getKey());

                                         if (aCounter == null) {

                                                 aggregated.put(entry.getKey(), new AtomicLong(value));

                                         } else {

                                                 aCounter.addAndGet(value);

                                         }

                                 }

                         }

                 }

                 boolean flush = false;

                 for (AtomicLong val: aggregated.values()) {

                         if (val.get() != 0) {

                                 flush = true;

                         }

                 }

                 if (!flush) {

                         return;

                 }

                 charBuffer.clear();

                 charBuffer.append("<serie timestamp=\"");

                 charBuffer.append(Long.toString(System.currentTimeMillis()));

                 charBuffer.append("\">\n");

                 for (Map.Entry<String, AtomicLong> entry: aggregated.entrySet()) {

                         charBuffer.append("  <item key=\"");

                         charBuffer.append(entry.getKey());

                         charBuffer.append("\" value=\"");

                         long value = entry.getValue().get();

                         charBuffer.append(Long.toString(value));

                         entry.getValue().addAndGet(-value);

                         charBuffer.append("\"/>\n");

                 }

                 charBuffer.append("</serie>\n");

                 charBuffer.append(CLOSING_TAG);

                 charBuffer.flip();

                 byteBuffer.clear();

                 encoder.encode(charBuffer, byteBuffer, true);

                 byteBuffer.flip();

                 try {

                         fileChannel.position(fileChannel.position() - CLOSING_TAG.length());

                         while (byteBuffer.hasRemaining()) {

                                 fileChannel.write(byteBuffer);

                         }

                         fileChannel.force(true);

                 } catch (IOException e) {

                         e.printStackTrace();

                 }

         }

         public void setFilename(String filename) {

                 this.filename = filename;

         }

         public void setInterval(long interval) {

                 this.interval = interval;

         }

 }